The California sea otter, whose luscious coat was so coveted by fur traders that the species was nearly wiped out, is holding steady in its west coast sanctum despite a record number of deaths, including an alarming uptick in shark attacks.

The population of southern sea otters, as the local creatures are known, has increased 1.5 percent per year since 2010, according to the annual U.S. Geological Survey population count released Tuesday.

The modest increase comes despite the fact that a record 335 sea otters were found dead in 2011, many of them from shark bites. That's more deaths in a year than have ever been recorded.

"That is definitely a pattern that has raised a lot of eyebrows and a lot of questions about what is happening in the near-shore habitat," said Tim Tinker, a research biologist for the Geological Survey and the organization's lead scientist for otter studies. Shark attacks were "the largest single source of mortality this year, which is something quite new."

The number of bite wounds found on the otters, almost all of which appear to be from great white sharks, were perplexing to scientists considering that only 339 of the toothy predators were recently counted in local waters, far fewer than researchers expected.

The southern sea otter once frolicked from Alaska's Prince William Sound to Baja California with as many 15,000 at the time of the Declaration of Independence. Then, starting in the late 1700s, fur hunters began killing them by the thousands for their luxurious pelts.

Otters were thought to be extinct in California by 1938, when a small population of about 50 was discovered near Big Sur. In 1977, they were listed as threatened under the Endangered Species Act.

The Geological Survey count has been done every year since 1985 in early autumn and late spring along 375 miles of coastal waters from Half Moon Bay to Santa Barbara.

Otter aficionados were upset in 2010 when the number of sea otters declined 3.6 percent compared with the year before. It was the second straight decline after a decade of small but encouraging increases. Even more disturbing was an 11 percent drop in the number of otter pups compared with the year before.

Unusual weather conditions prevented a count in 2011, so this year's survey was highly anticipated.

In addition to the increase in adult otters, there were also more otter pups in areas where they were rare, including 10 pups southeast of Point Conception, the highest on record, according to the report.

"This is good news," said Brad Hunt, the program manager for the Otter Project. "The raw sea otter count and three-year average are both up, and the pup count is the third highest on record. These increases all occurred during two record years of mortality."

Tinker said he too is cautiously optimistic, but believes the local otter population should be growing faster than it has considering how much open habitat there is along the California coast.

Researchers say little can be done about natural predation. Instead, they insist, regulators should be working to reduce human-caused otter mortality, including boat strikes, pollution and toxic algae blooms that form in stagnant fresh water and then flow out to the ocean.

"The recovery is still slow and we don't know all the reasons, but we do know the number of deaths is greater than 10 percent of the population, one of the highest mortality rates in a wildlife population," said Jim Curland, the advocacy program director for the Carmel nonprofit Friends of the Sea Otter. "It's better than getting results that are going in a downward direction, but our work is still cut out for us."